regulator: max14577: Add error check for max14577_read_reg()

The function max14577_reg_get_current_limit() calls the function
max14577_read_reg(), but does not check its return value. A proper
implementation can be found in max14577_get_online().

Add a error check for the max14577_read_reg() and return error code
if the function fails.

Fixes: b0902bbe ("regulator: max14577: Add regulator driver for Maxim 14577")
Cc: stable@vger.kernel.org # v3.14
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Link: https://patch.msgid.link/20250526025627.407-1-vulab@iscas.ac.cn


Signed-off-by: Mark Brown <broonie@kernel.org>